SARA catalog was a helpful initial source to find print sources and books using the keywords from tab: Finding Research Tools.
Note: While some items in SARA are electronic versions of articles and can be viewed, many times, these items could not be saved (i.e.: PDF files). Therefore, if one is looking to be able to save the document, there may be some difficulty.
For those who are searching in non-BLS websites, Worldcat is also useful, especially for its Interlibrary Loan (ILL) feature. For instance, Columbia Law School has a treatise which is unavailable at BLS, Law of the Sea in Dialogue. Through the ILL function, a researcher may find this book. Additionally, a researcher may go directly to Columbia Law School's Library website.
Note: these books were generated by using the search terms stated before in Finding Research Sources. I have listed them from most recently to least recently published.